为什么我的矩形在我的JPanel中以奇怪的形式出现？

Question

当我运行我的代码时，只有在JPanel的左上角单击鼠标时才会显示一个矩形。当它出现时，它会变形变形。如果我将fillRect更改为fillOval，它根本不显示。我的目标是在点击鼠标时在鼠标位置填充一个圆圈。我的代码是：

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class PaintProgram {
    JFrame frame;
    JPanel panel;
    Point p;
    int x;
    int y;
    int diameter;
    public PaintProgram(){
        frame = new JFrame();
        frame.setSize(500,500);
        panel = new JPanel();
        diameter = 100;
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        panel.addMouseListener(new MListener());
        panel.add(new DrawCircle());
        frame.add(panel);
        frame.setVisible(true);
    }

    public static void main(String[] args){
        PaintProgram p = new PaintProgram();
    }

    class UBListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent a){

        }
    }


    class MListener implements MouseListener{
        public void mousePressed(MouseEvent e){
            p = panel.getMousePosition();
            x = (int) p.getX();
            y = (int) p.getY();
            panel.add(new DrawCircle());
            frame.repaint();
            frame.revalidate();
            System.out.println(x + "," + y);
        }

        public void mouseReleased(MouseEvent e){
        }

        public void mouseClicked(MouseEvent e){
        }

        public void mouseExited(MouseEvent e){
        }

        public void mouseEntered(MouseEvent e){
        }
    }

    class DrawCircle extends JPanel{
        @Override
        public void paintComponent(Graphics g){
            super.paintComponent(g);
            g.setColor(Color.orange);
            g.fillRect(x,y,diameter,diameter);
            System.out.println(x + "," + y);
        }
    }
}

Answer 1

我认为您的代码存在一些问题。首先，您在PaintProgram中定义的JPanel不是必需的，并且在您的代码中导致了一些问题。基本上我已经切换到使用JFrame几乎所有东西。接下来，我不认为你想在DrawCircle()中创建一个新的PaintProgram，只需点击鼠标即可。

以下代码适用于我（每当你点击时在你的光标周围绘制一个圆圈，我认为这就是你想要的）。我做了一些我没有提到的改动，所以随便提问。

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;

public class PaintProgram {
    JFrame frame;
    Point p;
    int x;
    int y;
    int diameter;
    public PaintProgram(){
        frame = new JFrame();
        frame.setSize(500,500);
        diameter = 100;
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.addMouseListener(new MListener());
        frame.setVisible(true);
    }

    public static void main(String[] args){
        PaintProgram p = new PaintProgram();
    }

    class UBListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent a){

        }
    }


    class MListener extends MouseAdapter {
       @Override
       public void mousePressed(MouseEvent e){
            p = frame.getMousePosition();
            x = (int) p.getX();
            y = (int) p.getY();
            frame.add(new DrawCircle());
            frame.repaint();
            frame.revalidate();
            System.out.println(x + "," + y);
        }
    }

    class DrawCircle extends JPanel{
        @Override
        public void paintComponent(Graphics g){
            g.setColor(Color.orange);
            g.fillOval(x - 56, y - 77, diameter, diameter);
            System.out.println(x + "," + y);
        }
    }
}